Cable jackets having designed microstructures and methods for making cable jackets having designed microstructures

ABSTRACT

Optical fiber cables ( 1001 ) comprising at least one optical fiber transmission medium ( 1006 ) and at least one elongated polymeric protective component ( 1002 ) surrounding at least a portion of the optical fiber transmission medium. The elongated polymeric protective component ( 1002 ) comprises a polymeric matrix material and a plurality of microcapillaries containing a polymeric microcapillary material, where the polymeric matrix material has a higher flexural modulus than the polymeric microcapillary material. Also disclosed are dies and methods for making such optical fiber cables and protective components.

REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 62/094,439, filed on Dec. 19, 2014.

FIELD

Various embodiments of the present invention relate to cable coatingsand jackets having microcapillary structures.

INTRODUCTION

Optical fibers efficiently transmit information at high rates and overlong distances. These fibers are delicate and need to be protected. Inpractical application, a fiber optic cable protects the fibers frommechanical damage and/or adverse environmental conditions such asmoisture exposure. For example, specific protective components includeextruded buffer tubes, core tubes, and slotted core members.

Buffer tubes, also known as loose buffer tubes, are protectioncomponents used to house and protect optical fibers, such as in a cable.Typically, these loose buffer tubes are filled with a hydrocarbon gel orgrease to suspend and protect the fiber from moisture and have stringentrequirements for high crush resistance, resistance to micro-bending, lowbrittleness temperature, good grease compatibility, impact resistance,and low post-extrusion shrinkage. Materials used in the manufacture ofthe buffer tubes include polybutylene terephthalate (“PBT”), impactmodified high-crystallinity polypropylene, high impact copolymerpolypropylene and to a lesser extent high-density polyethylene. Amongstthese, PBT is a higher cost, higher density material, and cost-effectivealternatives are desired.

SUMMARY

One embodiment is an optical fiber cable, comprising:

-   -   (a) at least one optical fiber transmission medium; and    -   (b) at least one elongated polymeric protective component        surrounding at least a portion of said optical fiber        transmission medium,    -   wherein said elongated polymeric protective component comprises        a polymeric matrix material and a plurality of microcapillaries        which extend substantially in the direction of elongation of        said elongated polymeric protective component,    -   wherein at least a portion of said microcapillaries contain a        polymeric microcapillary material,    -   wherein said polymeric matrix material has a higher flexural        modulus than said polymeric microcapillary material.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the accompanying drawings in which:

FIG. 1 is a perspective view, partially in cross-section, of an extruderwith a die assembly for manufacturing a microcapillary film;

FIG. 2A is a longitudinal-sectional view of a microcapillary film;

FIGS. 2B and 2C are cross-sectional views of a microcapillary film;

FIG. 2D is an elevated view of a microcapillary film;

FIG. 2E is a segment 2E of a longitudinal sectional view of themicrocapillary film, as shown in FIG. 2B;

FIG. 2F is an exploded view of a microcapillary film;

FIG. 2G is a cross-sectional view of a microcapillary film particularlydepicting a single-layer embodiment;

FIGS. 3A and 3B are schematic perspective views of variousconfigurations of extruder assemblies including an annular die assemblyfor manufacturing coextruded multi-layer annular microcapillary productsand air-filled multi-layer annular microcapillary products,respectively;

FIG. 4A is a schematic view of a microcapillary film havingmicrocapillaries with a fluid therein;

FIG. 4B is a cross-sectional view of a coextruded microcapillary film;

FIG. 4C is a cross-sectional view of an inventive air-filledmicrocapillary film;

FIG. 5 is a schematic view of an annular microcapillary tubing extrudedfrom a die assembly;

FIGS. 6A and 6B are perspective views of an annular microcapillarytubing;

FIGS. 7A-7D are partial cross-sectional, longitudinal cross-sectional,end, and detailed cross-sectional views, respectively, of an annular dieassembly in an asymmetric flow configuration;

FIGS. 8A-8D are partial cross-sectional, longitudinal cross-sectional,end, and detailed cross-sectional views, respectively, of an annular dieassembly in a symmetric flow configuration;

FIGS. 9A-9D are partial cross-sectional, longitudinal cross-sectional,end, and detailed cross-sectional views, respectively, of an annular dieassembly in a symmetric flow configuration;

FIG. 10 is a perspective view of a die insert for an annular dieassembly;

FIG. 11 is a cross-sectional view of a loose buffer tube optical fibercable; and

FIG. 12 is a partial cutaway view of a core tube optical fiber cable.

DETAILED DESCRIPTION

The present disclosure relates to die assemblies and extruders forproducing annular microcapillary products. Such annular microcapillaryproducts may be used in fabricating wire and cable articles ofmanufacture, such as by forming at least a portion of a polymericcoating (e.g., a jacket) or a polymeric protective component surroundinga conductive core.

The die assembly includes an annular die insert positioned betweenmanifolds and defining material flow channels therebetween for extrudinglayers of a thermoplastic material. The die insert has a tip havingmicrocapillary flow channels on an outer surface for insertion ofmicrocapillary material in microcapillaries between the extruded layersof thermoplastic material. The microcapillaries may contain a variety ofmaterials, such as other thermoplastic materials or elastomericmaterials, or may simply be void-space microcapillaries (i.e.,containing a gas, such as air). The die assemblies for producing annularmicrocapillary products are a variation of die assemblies for producingmulti-layer microcapillary films, both of which are described in greaterdetail, below.

Microcapillary Film Extruder

FIG. 1 depicts an example extruder (100) used to form a multi-layerpolymeric film (110) with microcapillaries (103). The extruder (100)includes a material housing (105), a material hopper (107), a screw(109), a die assembly (111) and electronics (115). The extruder (100) isshown partially in cross-section to reveal the screw (109) within thematerial housing (105). While a screw type extruder is depicted, avariety of extruders (e.g., single screw, twin screw, etc.) may be usedto perform the extrusion of the material through the extruder (100) anddie assembly (111). One or more extruders may be used with one or moredie assemblies. Electronics (115) may include, for example, controllers,processors, motors and other equipment used to operate the extruder.

Raw materials (e.g. thermoplastic materials) (117) are placed into thematerial hopper (107) and passed into the housing (105) for blending.The raw materials (117) are heated and blended by rotation of the screw(109) rotationally positioned in the housing (105) of the extruder(100). A motor (121) may be provided to drive the screw (109) or otherdriver to advance the raw materials (117). Heat and pressure are appliedas schematically depicted from a heat source T and a pressure source P(e.g., the screw (109)), respectively, to the blended material to forcethe raw material (117) through the die assembly (111) as indicated bythe arrow. The raw materials (117) are melted and conveyed through theextruder (100) and die assembly (111). The molten raw material (117)passes through die assembly (111) and is formed into the desired shapeand cross section (referred to herein as the ‘profile’). The dieassembly (111) may be configured to extrude the molten raw material(117) into thin sheets of the multi-layer polymeric film (110) as isdescribed further herein.

Microcapillary Film

FIGS. 2A-2F depict various views of a multi-layer film (210) which maybe produced, for example, by the extruder (100) and die assembly (111)of FIG. 1. As shown in FIGS. 2A-2F, the multi-layer film (210) is amicrocapillary film. The multi-layer film (210) is depicted as beingmade up of multiple layers (250 a, b) of thermoplastic material. Thefilm (210) also has channels (220) positioned between the layers (250 a,b).

The multi-layer film (210) may also have an elongate profile as shown inFIG. 2C. This profile is depicted as having a wider width W relative toits thickness T. The width W may be in the range of from 3 inches (7.62cm) to 60 inches (152.40 cm) and may be, for example, 24 inches (60.96cm) in width, or in the range of from 20 to 40 inches (50.80-101.60 cm),or in the range of from 20 to 50 inches (50.80-127 cm), etc. Thethickness T may be in the range of from 100 to 2,000 μm (e.g., from 250to 2000 μm). The channels (220) may have a dimension φ (e.g., a width ordiameter) in the range of from 50 to 500 μm (e.g., from 100 to 500 μm,or 250 to 500 μm), and have a spacing S between the channels (220) inthe range of from 50 to 500 μm (e.g., from 100 to 500 μm, or 250 to 500μm). As further described below, the selected dimensions may beproportionally defined. For example, the channel dimension φ may be adiameter of about 30% of thickness T.

As shown, layers (250 a, b) are made of a matrix thermoplastic materialand channels (220) have a channel fluid (212) therein. The channel fluidmay comprise, for example, various materials, such as air, gas,polymers, etc., as will be described further herein. Each layer (250 a,b) of the multi-layer film (210) may be made of various polymers, suchas those described further herein. Each layer may be made of the samematerial or of a different material. While only two layers (250 a, b)are depicted, the multi-layer film (210) may have any number of layersof material.

It should be noted that when the same thermoplastic material is employedfor the layers (250 a, b), then a single layer (250) can result in thefinal product, due to fusion of the two streams of the matrix layerscomprised of the same polymer in a molten state merging shortly beforeexiting the die. This phenomenon is depicted in FIG. 2G.

Channels (220) may be positioned between one or more sets of layers (250a, b) to define microcapillaries (252) therein. The channel fluid (212)may be provided in the channels (220). Various numbers of channels (220)may be provided as desired. The multiple layers may also have the sameor different profiles (or cross-sections). The characteristics, such asshape of the layers (250 a, b) and/or channels (220) of the multi-layerfilm (210), may be defined by the configuration of the die assembly usedto extrude the thermoplastic material as will be described more fullyherein.

The microcapillary film (210) may have a thickness in the range of from100 μm to 3,000 μm; for example, microcapillary film or foam (210) mayhave a thickness in the range of from 100 to 2,000 μm, from 100 to 1,000μm, from 200 to 800 μm, from 200 to 600 μm, from 300 to 1,000 μm, from300 to 900 μm, or from 300 to 700 μm. Thefilm-thickness-to-microcapillary-diameter ratio can be in the range offrom 2:1 to 400:1.

The microcapillary film (210) may comprise at least 10 percent by volume(“vol %”) of the matrix (218), based on the total volume of themicrocapillary film (210); for example, the microcapillary film (210)may comprise from 10 to 80 vol % of the matrix (218), from 20 to 80 vol% of the matrix (218), or from 30 to 80 vol % of the matrix (218), basedon the total volume of the microcapillary film (210).

The microcapillary film (210) may comprise from 20 to 90 vol % ofvoidage, based on the total volume of the microcapillary film (210); forexample, the microcapillary film (210) may comprise from 20 to 80 vol %of voidage, from 20 to 70 vol % of voidage, or from 30 to 60 vol % ofvoidage, based on the total volume of the microcapillary film (210).

The microcapillary film (210) may comprise from 50 to 100 vol % of thechannel fluid (212), based on the total voidage volume, described above;for example, the microcapillary film (210) may comprise from 60 to 100vol % of the channel fluid (212), from 70 to 100 vol % of the channelfluid (212), or from 80 to 100 vol % of the channel fluid (212), basedon the total voidage volume, described above.

The microcapillary film (210) has a first end (214) and a second end(216). One or more channels (220) are disposed in parallel in the matrix(218) from the first end (214) to the second end (216). The one or morechannels (220) may be, for example, at least about 250 μm apart fromeach other. The one or more channels (220) can have a diameter of atleast 250 μm, or in the range of from 250 to 1990 μm, from 250 to 990μm, from 250 to 890 μm, from 250 to 790 μm, from 250 to 690 μm, or from250 to 590 μm. The one or more channels (220) may have a cross sectionalshape selected from the group consisting of circular, rectangular, oval,star, diamond, triangular, square, the like, and combinations thereof.The one or more channels (220) may further include one or more seals atthe first end (214), the second end (216), therebetween the first end(214) and the second end (216), or combinations thereof.

The matrix (218) comprises one or more matrix thermoplastic materials.Such matrix thermoplastic materials include, but are not limited to,polyolefins (e.g., polyethylenes, polypropylenes, etc.); polyamides(e.g., nylon 6); polyvinylidene chloride; polyvinylidene fluoride;polycarbonate; polystyrene; polyethylene terephthalate; polyurethane;and polyester. Specific examples of matrix thermoplastic materialsinclude those listed on pages 5 through 11 of PCT Published ApplicationNo. WO 2012/094315, titled “Microcapillary Films and Foams ContainingFunctional Filler Materials,” which are herein incorporated byreference.

The matrix (218) may be reinforced via, for example, glass or carbonfibers and/or any other mineral fillers such talc or calcium carbonate.Exemplary fillers include, but are not limited to, natural calciumcarbonates (e.g., chalks, calcites and marbles), synthetic carbonates,salts of magnesium and calcium, dolomites, magnesium carbonate, zinccarbonate, lime, magnesia, barium sulphate, barite, calcium sulphate,silica, magnesium silicates, talc, wollastonite, clays and aluminumsilicates, kaolins, mica, oxides or hydroxides of metals or alkalineearths, magnesium hydroxide, iron oxides, zinc oxide, glass or carbonfiber or powder, wood fiber or powder or mixtures of these compounds.

The one or more channel fluids (212) may include a variety of fluids,such as air, other gases, or channel thermoplastic material. Channelthermoplastic materials include, but are not limited to, polyolefins(e.g., polyethylenes, polypropylenes, etc.); polyamides (e.g., nylon 6);polyvinylidene chloride; polyvinylidene fluoride; polycarbonate;polystyrene; polyethylene terephthalate; polyurethane; and polyester. Aswith the matrix (218) materials discussed above, specific examples ofthermoplastic materials suitable for use as channel fluids (212) includethose listed on pages 5 through 11 of PCT Published Application No. WO2012/094315.

When a thermoplastic material is used as the channel fluid (212), it maybe reinforced via, for example, glass or carbon fibers and/or any othermineral fillers such talc or calcium carbonate. Exemplary reinforcingfillers include those listed above as suitable for use as fillers in thematrix (218) thermoplastic material.

Annular Microcapillary Product Extruder Assemblies

FIGS. 3A and 3B depict example extruder assemblies (300 a, b) used toform a multi-layer, annular microcapillary product (310 a, b) havingmicrocapillaries (303). The extruder assemblies (300 a, b) may besimilar to the extruder (100) of FIG. 1 as previously described, exceptthat the extruder assemblies (300 a, b) include multiple extruders (100a, b, c), with combined annular microcapillary co-extrusion dieassemblies (311 a, b) operatively connected thereto. The annular dieassemblies (311 a, b) have die inserts (353) configured to extrudemulti-layer, annular microcapillary products, such as film (310) asshown in FIGS. 4A-4C, tubing (310 a) as shown in FIGS. 5, 6A, and 6B,and/or molded shapes (310 b) as shown in FIG. 3B.

FIG. 3A depicts a first configuration of an extruder assembly (300 a)with three extruders (100 a, b, c) operatively connected to the combinedannular microcapillary co-extrusion die assembly (311 a). In an example,two of the three extruders may be matrix extruders (100 a, b) used tosupply thermoplastic material (e.g., polymer) (117) to the die assembly(311 a) to form layers of the annular microcapillary product (310 a). Athird of the extruders may be a microcapillary (or core layer) extruder(100 c) to provide a microcapillary material, such as a thermoplasticmaterial (e.g., polymer melt) (117), into the microcapillaries (303) toform a microcapillary phase (or core layer) therein.

The die insert (353) is provided in the die assembly (311 a) to combinethe thermoplastic material (117) from the extruders (100 a, b, c) intothe annular microcapillary product (310 a). As shown in FIG. 3A, themulti-layer, annular microcapillary product may be a blown tubing (310a) extruded upwardly through the die insert (353) and out the dieassembly (311 a). Annular fluid (312 a) from a fluid source (319 a) maybe passed through the annular microcapillary product (310 a) to shapethe multi-layer, annular microcapillary tubing (310 a) during extrusionas shown in FIG. 3A, or be provided with a molder (354) configured toproduce a multi-layer, annular microcapillary product in the form of anannular microcapillary molding (or molded product), such as a bottle(310 b) as shown in FIG. 3B.

FIG. 3B shows a second configuration of an extruder assembly (300 b).The extruder assembly (300 b) is similar to the extruder assembly (300a), except that the microcapillary extruder (100 c) has been replacedwith a microcapillary fluid source (319 b). The extruders (100 a, b)extrude thermoplastic material (as in the example of FIG. 3A) and themicrocapillary fluid source (319 b) may emit microcapillary material inthe form of a microcapillary fluid (312 b) through the die insert (353)of the die assembly (311 b). The two matrix extruders (100 a, b) emitthermoplastic layers, with the microcapillary fluid source (319 b)emitting microcapillary fluid (312 b) into the microcapillaries (303)therebetween to form the multi-layer, annular microcapillary product(310 b). In this version, the annular die assembly (311 b) may form filmor blown products as in FIG. 3A, or be provided with a molder (354)configured to produce a multi-layer, annular microcapillary product inthe form of an annular microcapillary molding (or molded product), suchas a bottle, (310 b).

While FIGS. 3A and 3B show each extruder (100 a, b, c) as having aseparate material housing (105), material hopper (107), screw (109),electronics (115), motor (121), part or all of the extruders (100) maybe combined. For example, the extruders (100 a, b, c) may each havetheir own hopper (107), and share certain components, such aselectronics (115) and die assembly (311 a, b). In some cases, the fluidsources (319 a, b) may be the same fluid source providing the same fluid(312 a, b), such as air.

The die assemblies (311 a, b) may be operatively connected to theextruders (100 a, b, c) in a desired orientation, such as a verticalupright position as shown in FIG. 3A, a vertical downward position asshown in FIG. 3B, or a horizontal position as shown in FIG. 1. One ormore extruders may be used to provide the polymeric matrix material thatforms the layers and one or more material sources, such as extruder (100c) and/or microcapillary fluid source (319 b), may be used to providethe microcapillary material. Additionally, as described in more detailbelow, the die assemblies may be configured in a crosshead position forco-extrusion with a conductor or conductive core.

Annular Microcapillary Products

FIGS. 4A-4C depict various views of a multi-layer, annularmicrocapillary product which may be in the form of a film (310, 310′)produced, for example, by the extruders (300 a, b) and die assemblies(311 a, b) of FIGS. 3A and/or 3B. As shown in FIGS. 4A and 4B, themulti-layer, annular microcapillary product (310) may be similar to themulti-layer film (210), except that the multi-layer, annularmicrocapillary product (310) is formed from the annular die assemblies(311 a, b) into polymeric matrix layers (450 a, b) with microcapillaries(303, 303′) therein. The polymeric matrix layers (450 a, b) collectivelyform a polymeric matrix (418) of the annular microcapillary product(310). The layers (450 a, b) have parallel, linear channels (320)defining microcapillaries (303) therein.

As shown in FIGS. 4B and 4C, the multi-layer, annular microcapillaryproduct (310, 310′) may be extruded with various microcapillary material(117) or microcapillary fluid (312 b) therein. The microcapillaries maybe formed in channels (320, 320′) with various cross-sectional shapes.In the example of FIG. 4B, the channels (320) have an arcuatecross-section defining the microcapillaries (303) with themicrocapillary material (117) therein. The microcapillary material (117)is in the channels (320) between the matrix layers (450 a, b) that formthe polymeric matrix (418). The microcapillary material (117) forms acore layer between the polymeric matrix layers (450 a, b).

In the example of FIG. 4C, the channels (320′) have another shape, suchas an elliptical cross-section defining microcapillaries (303′) with themicrocapillary material (312 b) therein. The microcapillary material(312 b) is depicted as fluid (e.g., air) in the channels (320′) betweenthe layers (450 a, b) that form the polymeric matrix (418).

It should be noted that, as with the films described above, the annularmicrocapillary product can also take the form of a single-layer productwhen the same matrix material is employed for the layers (450 a, b).This is due to the fusion of the two streams of the matrix layers in amolten state merging shortly before exiting the die.

The materials used to form the annular microcapillary products asdescribed herein may be selected for a given application. For example,the material may be a plastic, such as a thermoplastic or thermosetmaterial. When a thermoplastic material is employed, the thermoplasticmaterial (117) forming the polymeric matrix (418) and/or themicrocapillary material (117) may be selected from those materialsuseful in forming the film (210) as described above. Accordingly, theannular microcapillary products may be made of various materials, suchas polyolefins (e.g., polyethylene or polypropylene). For example, inFIGS. 4A and 4B, the polymeric matrix (418) may be a low-densitypolyethylene and the microcapillary material (117) may be polypropylene.As another example, in FIG. 4C the polymeric matrix (418) can be made oflow-density polyethylene with air as the microcapillary material (312b).

Referring to FIG. 5, the fluid source (319 a) may pass annular fluid(e.g., air) (312 a) through the annular microcapillary product (310 a)to support the tubular shape during extrusion. The die assembly (311 a)may form the multi-layer, annular microcapillary product (310 a, 310 a′)into a tubular shape as shown in FIGS. 6A-6B.

As also shown by FIGS. 6A and 6B, the thermoplastic materials formingportions of the multi-layer, annular microcapillary product (310 a, 310a′) may be varied. In the example shown in FIGS. 4A, 4B, and 6A, thelayers (450 a, b) forming polymeric matrix (418) may have a differentmaterial from the microcapillary material (117) in the microcapillaries(303) as schematically indicated by the black channels (320) and whitepolymeric matrix (418). In another example, as shown in FIG. 6B, thelayers (450 a, b) forming a polymeric matrix (418) and the material inmicrocapillaries (303) may be made of the same material, such aslow-density polyethylene, such that the polymeric matrix (418) and thechannels (320) are both depicted as black.

Die Assemblies for Annular Microcapillary Products

FIGS. 7A-9D depict example configurations of die assemblies (711, 811,911) usable as the die assembly (311). While FIGS. 7A-9D show examplesof possible die assembly configurations, combinations and/or variationsof the various examples may be used to provide the desired multi-layer,annular microcapillary product, such as those shown in the examples ofFIGS. 4A-6B.

FIGS. 7A-7D depict partial cross-sectional, longitudinalcross-sectional, end, and detailed cross-sectional views, respectively,of the die assembly (711). FIGS. 8A-8D depict partial cross-sectional,longitudinal cross-sectional, end, and detailed cross-sectional views,respectively, of the die assembly (811). FIGS. 9A-9D depict partialcross-sectional, longitudinal cross-sectional, end, and detailedcross-sectional views, respectively, of the die assembly (911). The dieassemblies (711, 811) may be used, for example, with the extruderassembly (300 a) of FIG. 3A and the die assembly (911) may be used, forexample, with the extruder assembly (300 b) of FIG. 3B to formmulti-layer, annular microcapillary products, such as those describedherein.

As shown in FIGS. 7A-7D the die assembly (711) includes a shell (758),an inner manifold (760), an outer manifold (762), a cone (764), and adie insert (768). The shell (758) is a tubular member shaped to receivethe outer manifold (762). The outer manifold (762), die insert (768),and the inner manifold (760) are each flange shaped members stacked andconcentrically received within the shell (758). While an inner manifold(760) and an outer manifold (762) are depicted, one or more inner and/orouter manifolds or other devices capable of providing flow channels forforming layers of the polymeric matrix may be provided.

The die insert (768) is positioned between the outer manifold (762) andthe inner manifold (760). The inner manifold (760) has the cone (764) atan end thereof extending through the die insert (768) and the outermanifold (762) and into the shell (758). The die assembly (711) may beprovided with connectors, such as bolts (not shown), to connect portionsof the die assembly (711).

Referring now to FIG. 7B, annular matrix channels (774 a, b) are definedbetween the shell (758) and the outer manifold (762) and between the dieinsert (768) and the inner manifold (760), respectively. Thethermoplastic material (117) is depicted passing through the matrixchannels (774 a, b) as indicated by the arrows to form the layers (450a, b) of the multi-layer, annular microcapillary product (710). Themulti-layer, annular microcapillary product (710) may be any of themulti-layer, annular microcapillary products described herein, such as(310 a, b).

A microcapillary channel (776) is also defined between the die insert(768) and the outer manifold (762). The microcapillary channel (776) maybe coupled to the microcapillary material source for passing themicrocapillary material (117, 312 b) through the die assembly (711) andbetween the layers (450 a, b) to form the microcapillaries (303)therein. The fluid channel (778) extends through the inner manifold(760) and the cone (764). Annular fluid (312 a) from fluid source (319a) flows through the fluid channel (778) and into the product (710 a,).

The die insert (768) may be positioned concentrically between the innermanifold (760) and the outer manifold (762) to provide uniformdistribution of polymer melt flow through the die assembly (711). Thedie insert (762) may be provided with a distribution channel (781) alongan outer surface thereof to facilitate the flow of the microcapillarymaterial (117/312 b) therethrough.

The matrix channels (774 a, b) and the microcapillary channel (776)converge at convergence (779) and pass through an extrusion outlet (780)such that thermoplastic material flowing through matrix channels (774 a,b) forms layers (450 a, b) with microcapillary material (117/312 b) frommicrocapillary channel (776) therebetween. The outer manifold (762) anddie insert (768) each terminate at an outer nose (777 a) and an insertnose (777 b), respectively. As shown in FIG. 7D, the outer nose (777 a)extends a distance A further toward the extrusion outlet (780) and/or adistance A further away from the extrusion outlet (780) than the nose(777 b).

The die assemblies (811, 911) of FIGS. 8A-9D may be similar to the dieassembly (711) of FIGS. 7A-7D, except that a position of noses (777 a,b, 977 a, b) of the die insert (768, 968) relative to the outer manifold(762) may be varied. The position of the noses may be adjusted to definea flow pattern, such as asymmetric or symmetric therethrough. As shownin FIGS. 7A-7D, the die assembly (711) is in an asymmetric flowconfiguration with nose (777 b) of the die insert (768) positioned adistance A from the nose (777 a) of the outer manifold (762). As shownin FIGS. 8A-8D, the die assembly (811) is in the symmetric flowconfiguration with the noses (777 a, b) of the die insert (768) and theouter manifold (762) being flush.

FIGS. 9A-9D and 10 depict an annular die insert (968) provided withfeatures to facilitate the creation of the channels (320),microcapillaries (303), and/or insertion of the microcapillary material(117/312 b) therein (see, e.g., FIGS. 4A-4B). The die insert (968)includes a base (982), a tubular manifold (984), and a tip (986). Thebase (982) is a ring shaped member that forms a flange extending from asupport end of the annular microcapillary manifold (984). The base (982)is supportable between the inner manifold (760) and outer manifold(762). The outer manifold (762) has an extended nose (977 a) and the dieinsert (968) has an extended nose (977 b) positioned flush to each otherto define a symmetric flow configuration through the die assembly (911).

The tip (986) is an annular member at a flow end of the tubular manifold(984). An inner surface of the tip (986) is inclined and shaped toreceive an end of the cone (764). The tip (986) has a larger outerdiameter than the annular microcapillary manifold (984) with an inclinedshoulder (990) defined therebetween. An outer surface of the tip (986)has a plurality of linear, parallel microcapillary flow channels (992)therein for the passage of the microcapillary material (117/312 b)therethrough. The outer manifold 762 terminates in a sharp edge (983 a)along nose (977 a) and tip (986) terminates in a sharp edge (983 b)along nose (977 b).

The annular microcapillary manifold (984) is an annular member extendingbetween the base (982) and the tip (986). The annular microcapillarymanifold (984) is supportable between a tubular portion of the innermanifold (760) and the outer manifold (762). The annular microcapillarymanifold (984) has a passage (988) therethrough to receive the innermanifold (760).

The distribution channel (781) may have a variety of configurations. Asshown in FIGS. 9A-9D, an outer surface of the annular microcapillarymanifold (984) has the distribution channel (781) therealong for thepassage of material therethrough. The distribution channel (781) may bein fluid communication with the microcapillary material (117/312 b) viathe microcapillary channel (776) as schematically depicted in FIG. 9B.The distribution channel (781) may be positioned about the die insert(968) to direct the microcapillary material around a circumference ofthe die insert (968). The die insert (968) and/or distribution channel(781) may be configured to facilitate a desired amount of flow ofmicrocapillary material (117/312 b) through the die assembly. Thedistribution channel (781) defines a material flow path for the passageof the microcapillary material between the die insert (968) and theouter manifold (762). A small gap may be formed between the die insert(968) and the outer manifold (762) that allows the microcapillarymaterial (117/312 b) to leak out of the distribution channel (781) todistribute the microcapillary material (117/312 b) uniformly through thedie assembly (911). The distribution channel (781) may be in the form ofa cavity or channel extending a desired depth into the die insert (968)and/or the outer manifold (760). For example, as shown in FIGS. 7A-9D,the distribution channel (781) may be a space defined between the outersurface of the die insert (968) and the outer manifold (760). As shownin FIG. 10, the distribution channel (781, 1081) is a helical grooveextending a distance along the outer surface of the tubular manifold(984). Part or all of the distribution channel (781, 1081) may belinear, curved, spiral, cross-head, and/or combinations thereof.

Coated Conductor

The above-described annular microcapillary products can be used toprepare coated conductors, such as a cable. “Cable” and “power cable”mean at least one conductor within a sheath, e.g., an insulationcovering and/or a protective outer jacket. “Conductor” denotes one ormore wire(s) or fiber(s) for conducting heat, light, and/or electricity.The conductor may be a single-wire/fiber or a multi-wire/fiber and maybe in strand form or in tubular form. Non-limiting examples of suitableconductors include metals such as silver, gold, copper, carbon, andaluminum. The conductor may also be optical fiber made from either glassor plastic. “Wire” means a single strand of conductive metal, e.g.,copper or aluminum, or a single strand of optical fiber. Typically, acable is two or more wires or optical fibers bound together, often in acommon insulation covering and/or protective jacket. The individualwires or fibers inside the sheath may be bare, covered or insulated.Combination cables may contain both electrical wires and optical fibers.When the cable is a power cable, the cable can be designed for low,medium, and/or high voltage applications. Typical cable designs areillustrated in U.S. Pat. Nos. 5,246,783, 6,496,629 and 6,714,707. Whenthe cable is a telecommunication cable, the cable can be designed fortelephone, local area network (LAN)/data, coaxial CATV, coaxial RF cableor a fiber optic cable.

The above-described annular microcapillary products can constitute atleast one polymeric coating layer in a cable, which is elongated in thesame direction of elongation as the conductor or conductive core of thecable. As such, the polymeric coating can surround at least a portion ofthe conductor. In surrounding the conductor, the polymeric coating canbe either in direct contact with the conductor or can be in indirectcontact with the conductor by being placed on one or more intercedinglayers between the conductor and the polymeric coating. The polymericcoating comprises a polymeric matrix material and a plurality ofmicrocapillaries which extend substantially in the direction ofelongation of the polymeric coating. In various embodiments, themicrocapillaries can be radially placed around the polymeric coating.Additionally, the microcapillaries can be spaced apart equidistantly orsubstantially equidistantly relative to one another.

One or more of the above-described die assemblies for producing annularmicrocapillary products can be modified to permit a conductor to passtherethrough, thereby allowing the polymeric coating comprising apolymeric matrix material and a plurality of microcapillaries to becoextruded onto the conductor or an interceding layer. Such aconfiguration is commonly known in the art as a crosshead die (see,e.g., US 2008/0193755 A1, US 2014/0072728 A1, and US 2013/0264092 A1).Specifically, the inner manifold (760) and cone (764) in FIGS. 7A, 8Aand 9A can be modified to create a wire- or conductor-passing hole. Asone of ordinary skill in the art would recognize, all the parts close tothe die exit can be modified such that the multilayer extrusionmaterials are able to coat onto a conductor or interceding layer,traveling through the wire- or conductor-passing hole. An additionalpart with molding passage can be fabricated. Such modifications arewithin the capabilities of one having ordinary skill in the art.

In an exemplary microcapillary extrusion coating process, a conductorcore through an extrusion coating equipment can be pulled by a retractorto continuously move through the wire-passing hole of the inner manifold(760) to go through the projection end and then pass through the moldingpassage of the outer die. While the conductor core is moving, thepolymer melt is injected by pressure into the material-supplyingpassages, flows toward to the wiring coating passage, and then into themolding passage at the outlet to coat onto the outer surface of theconductor core which is passing through the molding passage.Subsequently, the coated conductor core continues to move through themolding passage to outside the die, and then it can be cooled andhardened.

In preparing the polymeric coating, any of the above-described polymerscan be used as the polymeric matrix material. In various embodiments,the polymer employed as the polymeric matrix material can comprise anethylene-based polymer. As used herein, “ethylene-based” polymers arepolymers prepared from ethylene monomers as the primary (i.e., greaterthan 50 weight percent (“wt %”)) monomer component, though otherco-monomers may also be employed. “Polymer” means a macromolecularcompound prepared by reacting (i.e., polymerizing) monomers of the sameor different type, and includes homopolymers and interpolymers.“Interpolymer” means a polymer prepared by the polymerization of atleast two different monomer types. This generic term includes copolymers(usually employed to refer to polymers prepared from two differentmonomer types), and polymers prepared from more than two differentmonomer types (e.g., terpolymers (three different monomer types) andtetrapolymers (four different monomer types)).

In various embodiments, the ethylene-based polymer can be an ethylenehomopolymer. As used herein, “homopolymer” denotes a polymer comprisingrepeating units derived from a single monomer type, but does not excluderesidual amounts of other components used in preparing the homopolymer,such as chain transfer agents.

In an embodiment, the ethylene-based polymer can be anethylene/alpha-olefin (“α olefin”) interpolymer having an α-olefincontent of at least 1 wt %, at least 5 wt %, at least 10 wt %, at least15 wt %, at least 20 wt %, or at least 25 wt % based on the entireinterpolymer weight. These interpolymers can have an α-olefin content ofless than 50 wt %, less than 45 wt %, less than 40 wt %, or less than 35wt % based on the entire interpolymer weight. When an α-olefin isemployed, the α-olefin can be a C3-20 (i.e., having 3 to 20 carbonatoms) linear, branched or cyclic α-olefin. Examples of C3-20 α-olefinsinclude propene, 1 butene, 4-methyl-1-pentene, 1-hexene, 1-octene,1-decene, 1 dodecene, 1 tetradecene, 1 hexadecene, and 1-octadecene. Theα-olefins can also have a cyclic structure such as cyclohexane orcyclopentane, resulting in an α-olefin such as 3 cyclohexyl-1-propene(allyl cyclohexane) and vinyl cyclohexane. Illustrativeethylene/α-olefin interpolymers include ethylene/propylene,ethylene/1-butene, ethylene/1 hexene, ethylene/1 octene,ethylene/propylene/1-octene, ethylene/propylene/1-butene, andethylene/1-butene/1 octene.

Ethylene-based polymers also include interpolymers of ethylene with oneor more unsaturated acid or ester monomers, such as unsaturatedcarboxylic acids or alkyl (alkyl)acrylates. Such monomers include, butare not limited to, vinyl acetate, methyl acrylate, methyl methacrylate,ethyl acrylate, ethyl methacrylate, butyl acrylate, acrylic acid, andthe like. Accordingly, ethylene-based polymers can include interpolymerssuch as poly(ethylene-co-methyl acrylate) (“EMA”),poly(ethylene-co-ethyl acrylate) (“EEA”), poly(ethylene-co-butylacrylate) (“EBA”), and poly(ethylene-co-vinyl acetate) (“EVA”).

In various embodiments, the ethylene-based polymer can be used alone orin combination with one or more other types of ethylene-based polymers(e.g., a blend of two or more ethylene-based polymers that differ fromone another by monomer composition and content, catalytic method ofpreparation, etc). If a blend of ethylene-based polymers is employed,the polymers can be blended by any in-reactor or post-reactor process.

In an embodiment, the ethylene-based polymer can be a low-densitypolyethylene (“LDPE”). LDPEs are generally highly branched ethylenehomopolymers, and can be prepared via high pressure processes (i.e.,HP-LDPE). LDPEs suitable for use herein can have a density ranging from0.91 to 0.94 g/cm3. In various embodiments, the ethylene-based polymeris a high-pressure LDPE having a density of at least 0.915 g/cm³, butless than 0.94 g/cm³, or in the range of from 0.924 to 0.938 g/cm³.Polymer densities provided herein are determined according to ASTMInternational (“ASTM”) method D792. LDPEs suitable for use herein canhave a melt index (I₂) of less than 20 g/10 min., or ranging from 0.1 to10 g/10 min., from 0.5 to 5 g/10 min., from 1 to 3 g/10 min., or an 12of 2 g/10 min. Melt indices provided herein are determined according toASTM method D1238. Unless otherwise noted, melt indices are determinedat 190° C. and 2.16 Kg (i.e., 12). Generally, LDPEs have a broadmolecular weight distribution (“MWD”) resulting in a relatively highpolydispersity index (“PDI;” ratio of weight-average molecular weight tonumber-average molecular weight).

In an embodiment, the ethylene-based polymer can be a linear-low-densitypolyethylene (“LLDPE”). LLDPEs are generally ethylene-based polymershaving a heterogeneous distribution of comonomer (e.g., α-olefinmonomer), and are characterized by short-chain branching. For example,LLDPEs can be copolymers of ethylene and α-olefin monomers, such asthose described above. LLDPEs suitable for use herein can have a densityranging from 0.916 to 0.925 g/cm³. LLDPEs suitable for use herein canhave a melt index (I₂) ranging from 1 to 20 g/10 min., or from 3 to 8g/10 min.

In an embodiment, the ethylene-based polymer can be a very-low-densitypolyethylene (“VLDPE”). VLDPEs may also be known in the art asultra-low-density polyethylenes, or ULDPEs. VLDPEs are generallyethylene-based polymers having a heterogeneous distribution of comonomer(e.g., α-olefin monomer), and are characterized by short-chainbranching. For example, VLDPEs can be copolymers of ethylene andα-olefin monomers, such as one or more of those α-olefin monomersdescribed above. VLDPEs suitable for use herein can have a densityranging from 0.87 to 0.915 g/cm³. VLDPEs suitable for use herein canhave a melt index (I₂) ranging from 0.1 to 20 g/10 min., or from 0.3 to5 g/10 min.

In an embodiment, the ethylene-based polymer can be a medium-densitypolyethylene (“MDPE”). MDPEs are ethylene-based polymers havingdensities generally ranging from 0.926 to 0.950 g/cm³. In variousembodiments, the MDPE can have a density ranging from 0.930 to 0.949g/cm³, from 0.940 to 0.949 g/cm³, or from 0.943 to 0.946 g/cm³. The MDPEcan have a melt index (I₂) ranging from 0.1 g/10 min, or 0.2 g/10 min,or 0.3 g/10 min, or 0.4 g/10 min, up to 5.0 g/10 min, or 4.0 g/10 min,or, 3.0 g/10 min or 2.0 g/10 min, or 1.0 g/10 min, as determinedaccording to ASTM D-1238 (190° C./2.16 kg).

In an embodiment, the ethylene-based polymer can be a high-densitypolyethylene (“HDPE”). HDPEs are ethylene-based polymers generallyhaving densities greater than 0.940 g/cm³. In an embodiment, the HDPEhas a density from 0.945 to 0.97 g/cm³, as determined according to ASTMD-792. The HDPE can have a peak melting temperature of at least 130° C.,or from 132 to 134° C. The HDPE can have a melt index (I₂) ranging from0.1 g/10 min, or 0.2 g/10 min, or 0.3 g/10 min, or 0.4 g/10 min, up to5.0 g/10 min, or 4.0 g/10 min, or, 3.0 g/10 min or 2.0 g/10 min, or 1.0g/10 min, or 0.5 g/10 min, as determined according to ASTM D-1238 (190°C./2.16 kg). Also, the HDPE can have a PDI in the range of from 1.0 to30.0, or in the range of from 2.0 to 15.0, as determined by gelpermeation chromatography.

In an embodiment, the ethylene-based polymer can comprise a combinationof any two or more of the above-described ethylene-based polymers.

In an embodiment, the polymeric matrix material can comprise LDPE. In anembodiment, the polymeric matrix material is LDPE.

In an embodiment, the polymeric matrix material can comprise MDPE. In anembodiment, the polymeric matrix material is MDPE.

Production processes used for preparing ethylene-based polymers arewide, varied, and known in the art. Any conventional or hereafterdiscovered production process for producing ethylene-based polymershaving the properties described above may be employed for preparing theethylene-based polymers described herein. In general, polymerization canbe accomplished at conditions known in the art for Ziegler-Natta orKaminsky-Sinn type polymerization reactions, that is, at temperaturesfrom 0 to 250° C., or 30 or 200° C., and pressures from atmospheric to10,000 atmospheres (1,013 megaPascal (“MPa”)). In most polymerizationreactions, the molar ratio of catalyst to polymerizable compoundsemployed is from 10-12:1 to 10 1:1, or from 10-9:1 to 10-5:1.

Examples of suitable commercially available ethylene-based polymersinclude, but are not limited to AXELERON™ GP C-0588 BK (LDPE), AXELERON™FO 6548 BK (MDPE), AXELERON™ GP A-7530 NT (LLDPE), AXELERON™ GP G-6059BK (LLDPE), AXELERON™ GP K-3479 BK (HDPE), AXELERON™ GP A-1310 NT(HDPE), and AXELERON™ FO B-6549 NT (MDPE), all of which are commerciallyavailable from The Dow Chemical Company, Midland, Mich., USA.

Polypropylene-based polymers, such as homopolymer, random copolymer,heterophasic copolymer, and high-crystalline homopolymer polypropylenesare commercially available from Braskem Corp.

In preparing the polymeric coating, any of the above-described materialscan be used as the microcapillary material.

In various embodiments, the microcapillary material is a gas. In one ormore embodiments, the microcapillary material is air. In suchembodiments, the microcapillaries define individual, discrete voidspaces which are completely surrounded by the polymeric matrix materialwhen viewed as a cross-section taken orthogonal to the direction ofelongation of the microcapillaries. When the microcapillary material isa gas (e.g., air), the aggregate of void spaces defined by themicrocapillaries can constitute at least 10, at least 20, or at least 30volume percent (“vol %”) of the total volume of the polymeric coating.In various embodiments, the aggregate of void spaces defined by themicrocapillaries can constitute in the range of from 10 to 90 vol %,from 20 to 70 vol %, or from 30 to 60 vol % of the total volume of thepolymeric coating.

In one or more embodiments, the microcapillary material can be anelastomeric microcapillary material. As known in the art, elastomers aredefined as materials which experience large reversible deformationsunder relatively low stress. In any embodiments where themicrocapillaries are filled with a polymeric microcapillary material,the microcapillaries can define individual, discrete polymer-filledsegments which are completely surrounded by the polymeric matrixmaterial when viewed as a cross-section taken orthogonal to thedirection of elongation of the microcapillaries.

In various embodiments, the elastomer can be an olefin elastomer. Olefinelastomers include both polyolefin homopolymers and interpolymers.Examples of the polyolefin interpolymers are ethylene/α-olefininterpolymers and propylene/α-olefin interpolymers. In such embodiments,the α-olefin can be a C₃₋₂₀ linear, branched or cyclic α-olefin (for thepropylene/α-olefin interpolymers, ethylene is considered an α-olefin).Examples of C₃₋₂₀ α-olefins include propene, 1-butene,4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, and 1-octadecene. The α-olefins can alsocontain a cyclic structure such as cyclohexane or cyclopentane,resulting in an α-olefin such as 3-cyclohexyl-1-propene (allylcyclohexane) and vinyl cyclohexane. Although not α-olefins in theclassical sense of the term, for purposes of this invention certaincyclic olefins, such as norbornene and related olefins, are α-olefinsand can be used in place of some or all of the α-olefins describedabove. Similarly, styrene and its related olefins (for example,α-methylstyrene, etc.) are α-olefins for purposes of this invention.Illustrative polyolefin copolymers include ethylene/propylene,ethylene/butene, ethylene/1-hexene, ethylene/1-octene, ethylene/styrene,and the like. Illustrative terpolymers includeethylene/propylene/1-octene, ethylene/propylene/butene,ethylene/butene/1-octene, and ethylene/butene/styrene. The copolymerscan be random or blocky.

Olefin elastomers can also comprise one or more functional groups suchas an unsaturated ester or acid or silane, and these elastomers(polyolefins) are well known and can be prepared by conventionalhigh-pressure techniques. The unsaturated esters can be alkyl acrylates,alkyl methacrylates, or vinyl carboxylates. The alkyl groups can have 1to 8 carbon atoms and preferably have 1 to 4 carbon atoms. Thecarboxylate groups can have 2 to 8 carbon atoms and preferably have 2 to5 carbon atoms. The portion of the copolymer attributed to the estercomonomer can be in the range of 1 up to 50 percent by weight based onthe weight of the copolymer. Examples of the acrylates and methacrylatesare ethyl acrylate, methyl acrylate, methyl methacrylate, t-butylacrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexylacrylate. Examples of the vinyl carboxylates are vinyl acetate, vinylpropionate, and vinyl butanoate. Examples of the unsaturated acidsinclude acrylic acids or maleic acids. One example of an unsaturatedsilane is vinyl trialkoxysilane.

Functional groups can also be included in the olefin elastomer throughgrafting which can be accomplished as is commonly known in the art. Inone embodiment, grafting may occur by way of free radicalfunctionalization which typically includes melt blending an olefinpolymer, a free radical initiator (such as a peroxide or the like), anda compound containing a functional group. During melt blending, the freeradical initiator reacts (reactive melt blending) with the olefinpolymer to form polymer radicals. The compound containing a functionalgroup bonds to the backbone of the polymer radicals to form afunctionalized polymer. Exemplary compounds containing functional groupsinclude but are not limited to alkoxysilanes, e.g., vinyltrimethoxysilane, vinyl triethoxysilane, and vinyl carboxylic acids andanhydrides, e.g., maleic anhydride.

More specific examples of the olefin elastomers useful in this inventioninclude very-low-density polyethylene (“VLDPE”) (e.g., FLEXOMER™ethylene/1-hexene polyethylene made by The Dow Chemical Company),homogeneously branched, linear ethylene/α-olefin copolymers (e.g.TAFMER™ by Mitsui Petrochemicals Company Limited and EXACT™ by ExxonChemical Company), and homogeneously branched, substantially linearethylene/α-olefin polymers (e.g., AFFINITY™ and ENGAGE™ polyethyleneavailable from The Dow Chemical Company).

The olefin elastomers useful herein also include propylene, butene, andother alkene-based copolymers, e.g., copolymers comprising a majority ofunits derived from propylene and a minority of units derived fromanother α-olefin (including ethylene). Exemplary propylene polymersuseful herein include VERSIFY™ polymers available from The Dow ChemicalCompany, and VISTAMAXX™ polymers available from ExxonMobil ChemicalCompany.

Olefin elastomers can also include ethylene-propylene-diene monomer(“EPDM”) elastomers and chlorinated polyethylenes (“CPE”). Commercialexamples of suitable EPDMs include NORDEL™ EPDMs, available from The DowChemical Company. Commercial examples of suitable CPEs include TYRIN™CPEs, available from The Dow Chemical Company.

Olefin elastomers, particularly ethylene elastomers, can have a densityof less than 0.91 g/cm³ or less than 0.90 g/cm³. Ethylene copolymerstypically have a density greater than 0.85 g/cm³ or greater than 0.86,g/cm³.

Ethylene elastomers can have a melt index (I₂) greater than 0.10 g/10min., or greater than 1 g/10 min. Ethylene elastomers can have a meltindex of less than 500 g/10 min. or less than 100 g/10 min.

Other suitable olefin elastomers include olefin block copolymers (suchas those commercially available under the trade name INFUSE™ from TheDow Chemical Company, Midland, Mich., USA), mesophase-separated olefinmulti-block interpolymers (such as described in U.S. Pat. No.7,947,793), and olefin block composites (such as described in U.S.Patent Application Publication No. 2008/0269412, published on Oct. 30,2008).

In various embodiments, the elastomer useful as the microcapillarymaterial can be a non-olefin elastomer. Non-olefin elastomers usefulherein include silicone and urethane elastomers, styrene-butadienerubber (“SBR”), nitrile rubber, chloroprene, fluoroelastomers,perfluoroelastomers, polyether block amides and chlorosulfonatedpolyethylene. Silicone elastomers are polyorganosiloxanes typicallyhaving an average unit formula R_(a)SiO_((4-a)/2) which may have alinear or partially-branched structure, but is preferably linear. Each Rmay be the same or different. R is a substituted or non-substitutedmonovalent hydrocarbyl group which may be, for example, an alkyl group,such as methyl, ethyl, propyl, butyl, and octyl groups; aryl groups suchas phenyl and tolyl groups; aralkyl groups; alkenyl groups, for example,vinyl, allyl, butenyl, hexenyl, and heptenyl groups; and halogenatedalkyl groups, for example chloropropyl and 3,3,3-trifluoropropyl groups.The polyorganosiloxane may be terminated by any of the above groups orwith hydroxyl groups. When R is an alkenyl group the alkenyl group ispreferably a vinyl group or hexenyl group. Indeed alkenyl groups may bepresent in the polyorganosiloxane on terminal groups and/or polymer sidechains.

Representative silicone rubbers or polyorganosiloxanes include, but arenot limited to, dimethylvinylsiloxy-terminated polydimethylsiloxane,trimethylsiloxy-terminated polydimethylsiloxane,trimethylsiloxy-terminated copolymer of methylvinylsiloxane anddimethylsiloxane, dimethylvinylsiloxy-terminated copolymer ofmethylvinylsiloxane and dimethylsiloxane,dimethylhydroxysiloxy-terminated polydimethylsiloxane,dimethylhydroxysiloxy-terminated copolymer of methylvinylsiloxane anddimethylsiloxane, methylvinylhydroxysiloxy-terminated copolymer ofmethylvinylsiloxane and dimethylsiloxane,dimethylhexenylsiloxy-terminated polydimethylsiloxane,trimethylsiloxy-terminated copolymer of methylhexenylsiloxane anddimethylsiloxane, dimethylhexenylsiloxy-terminated copolymer ofmethylhexenylsiloxane and dimethylsiloxane,dimethylvinylsiloxy-terminated copolymer of methylphenylsiloxane anddimethylsiloxane, dimethylhexenylsiloxy-terminated copolymer ofmethylphenylsiloxane and dimethylsiloxane,dimethylvinylsiloxy-terminated copolymer ofmethyl(3,3,3-trifluoropropyl)siloxane and dimethylsiloxane, anddimethylhexenylsiloxy-terminated copolymer ofmethyl(3,3,3-trifluoropropyl)siloxane and dimethylsiloxane.

Urethane elastomers are prepared from reactive polymers such aspolyethers and polyesters and isocyanate functional organic compounds.One typical example is the reaction product of a dihydroxy functionalpolyether and/or a trihydroxy functional polyether with toluenediisocyanate such that all of the hydroxy is reacted to form urethanelinkages leaving isocyanate groups for further reaction. This type ofreaction product is termed a prepolymer which may cure by itself onexposure to moisture or by the stoichiometric addition of polycarbinolsor other polyfunctional reactive materials which react with isocyanates.The urethane elastomers are commercially prepared having various ratiosof isocyanate compounds and polyethers or polyesters.

The most common urethane elastomers are those containing hydroxylfunctional polyethers or polyesters and low molecular weightpolyfunctional, polymeric isocyanates. Another common material for usewith hydroxyl functional polyethers and polyesters is toluenediisocyanate.

Nonlimiting examples of suitable urethane rubbers include thePELLETHANE™ thermoplastic polyurethane elastomers available from theLubrizol Corporation; ESTANE™ thermoplastic polyurethanes, TECOFLEX™thermoplastic polyurethanes, CARBOTHANE™ thermoplastic polyurethanes,TECOPHILIC™ thermoplastic polyurethanes, TECOPLAST™ thermoplasticpolyurethanes, and TECOTHANE™ thermoplastic polyurethanes, all availablefrom Noveon; ELASTOLLAN™ thermoplastic polyurethanes and otherthermoplastic polyurethanes available from BASF; and additionalthermoplastic polyurethane materials available from Bayer, Huntsman,Lubrizol Corporation, Merquinsa and other suppliers. Preferred urethanerubbers are those so-called “millable” urethanes such as MILLATHANE™grades from TSI Industries.

Additional information on such urethane materials can be found inGolding, Polymers and Resins, Van Nostrande, 1959, pages 325 et seq. andSaunders and Frisch, Polyurethanes, Chemistry and Technology, Part II,Interscience Publishers, 1964, among others.

Suitable commercially available elastomers for use as the microcapillarymaterial include, but are not limited to, ENGAGE™ polyolefin elastomersavailable from The Dow Chemical Company, Midland, Mich., USA. A specificexample of such an elastomer is ENGAGE™ 8200, which is anethylene/octene copolymer having a melt index (I₂) of 5.0 and a densityof 0.870 g/cm³.

In embodiments where an elastomer microcapillary material is employed,it may be desirable for the matrix material to have higher toughness,abrasion resistance, density, and/or flexural modulus relative to theelastomer. This combination affords a polymeric coating having a toughouter layer but with increased flexibility compared to a coating formedcompletely of the same matrix material. For example, in variousembodiments, the polymeric coating can have one or more of theabove-described elastomers as the microcapillary material with anethylene-based polymer, a polyamide (e.g., nylon 6), polybutyleneterephthalate (“PBT”), polyethylene terephthalate (“PET”), apolycarbonate, or combinations of two or more thereof as the polymericmatrix material. In various embodiments, the polymeric coating cancomprise an olefin elastomer as the microcapillary material and thepolymeric matrix material can be selected from the group consisting ofHDPE, MDPE, LLDPE, LDPE, a polyamide, PBT, PET, a polycarbonate, orcombinations of two or more thereof. In one or more embodiments, themicrocapillary material can comprise an ethylene/octene copolymer olefinelastomer and the polymeric matrix material can comprise MDPE.

The above-described polymeric matrix material, microcapillary material,or both can contain one or more additives, such as those typically usedin preparing cable coatings. For example, the polymeric matrix material,microcapillary material, or both can optionally contain a non-conductivecarbon black commonly used in cable jackets. In various embodiments, theamount of a carbon black in the composition can be greater than zero(>0), typically from 1, more typically from 2, and up to 3 wt %, basedon the total weight of the composition. In various embodiments, thecomposition can optionally include a conductive filler, such as aconductive carbon black, metal fibers, powders, or carbon nanotubes, ata high level for semiconductive applications.

Non-limiting examples of conventional carbon blacks include the gradesdescribed by ASTM N550, N472, N351, N110 and N660, Ketjen blacks,furnace blacks and acetylene blacks. Other non-limiting examples ofsuitable carbon blacks include those sold under the tradenames BLACKPEARLS®, CSX®, ELFTEX®, MOGUL®, MONARCH®, REGAL® and VULCAN®, availablefrom Cabot.

The polymeric matrix material, microcapillary material, or both canoptionally contain one or more additional additives, which are generallyadded in conventional amounts, either neat or as part of a masterbatch.Such additives include, but not limited to, flame retardants, processingaids, nucleating agents, foaming agents, crosslinking agents, adhesionmodifiers, fillers, pigments or colorants, coupling agents,antioxidants, ultraviolet stabilizers (including UV absorbers),tackifiers, scorch inhibitors, antistatic agents, plasticizers,lubricants, viscosity control agents, anti-blocking agents, surfactants,extender oils, acid scavengers, metal deactivators, vulcanizing agents,and the like.

In one or more embodiments, the polymeric matrix material, themicrocapillary material, or both can be crosslinkable. Any suitablemethods known in the art can be used to crosslink the matrix materialand/or the microcapillary material. Such methods include, but are notlimited to, peroxide crosslinking, silane functionalization for moisturecrosslinking, UV crosslinking, or e-beam cure. Such crosslinking methodsmay require the inclusion of certain additives (e.g., peroxides), asknown in the art.

In various embodiments, the polymeric matrix material, themicrocapillary material, or both can contain one or more adhesionmodifiers. Adhesion modifiers may be helpful in improving interfacialadhesion between the matrix material and the microcapillary material.Any known or hereafter discovered additive that improves adhesionbetween two polymeric materials may be used herein. Specific examples ofsuitable adhesion modifiers include, but are not limited to, maleicanhydride (“MAH”) grafted resins (e.g., MAH-grafted polyethylene,MAH-grafted ethylene vinyl acetate, MAH-grafted polypropylene), aminatedpolymers (e.g., amino-functionalized polyethylene), and the like, andcombinations of two or more thereof. MAH-grafted resins are commerciallyavailable under the AMPLIFY™ GR trade name from The Dow Chemical Company(Midland, Mich., USA) and under the FUSABOND™ trade name from DuPont(Wilmington, Del., USA).

Non-limiting examples of flame retardants include, but are not limitedto, aluminum hydroxide and magnesium hydroxide.

Non-limiting examples of processing aids include, but are not limitedto, fatty amides such as stearamide, oleamide, erucamide, or N,N′ethylene bis-stearamide; polyethylene wax; oxidized polyethylene wax;polymers of ethylene oxide; copolymers of ethylene oxide and propyleneoxide; vegetable waxes; petroleum waxes; non-ionic surfactants; siliconefluids; polysiloxanes; and fluoroelastomers such as Viton® availablefrom Dupont Performance Elastomers LLC, or Dynamar™ available fromDyneon LLC.

A non-limiting example of a nucleating agent include Hyperform® HPN-20E(1,2 cyclohexanedicarboxylic acid calcium salt with zinc stearate) fromMilliken Chemicals, Spartanburg, S.C.

Non-limiting examples of fillers include, but are not limited to,various flame retardants, clays, precipitated silica and silicates,fumed silica, metal sulfides and sulfates such as molybdenum disulfideand barium sulfate, metal borates such as barium borate and zinc borate,metal anhydrides such as aluminum anhydride, ground minerals, andelastomeric polymers such as EPDM and EPR. If present, fillers aregenerally added in conventional amounts, e.g., from 5 wt % or less to 50or more wt % based on the weight of the composition.

In various embodiments, the polymeric coating on the coated conductorcan have a thickness ranging from 100 to 3,000 μm, from 500 to 3,000 μm,from 100 to 2,000 μm, from 100 to 1,000 μm, from 200 to 800 μm, from 200to 600 μm, from 300 to 1,000 μm, from 300 to 900 μm, or from 300 to 700μm.

Additionally, the average diameter of the microcapillaries in thepolymeric coating can be at least 50 μm, at least 100 μm, or at least250 μm. Additionally, the microcapillaries in the polymeric coating canhave an average diameter in the range of from 50 to 1,990 μm, from 50 to990 μm, from 50 to 890 μm, from 100 to 790 μm, from 150 to 690 μm, orfrom 250 to 590 μm. It should be noted that, despite the use of the termdiameter, the cross-section of the microcapillaries need not be round.Rather, they may take a variety of shapes, such as oblong as shown inFIGS. 4B and 4C. In such instances, the “diameter” shall be defined asthe longest dimension of the cross-section of the microcapillary. Thisdimension is illustrated as λ in FIG. 4B. The “average” diameter shallbe determined by taking three random cross-sections from a polymericcoating, measuring the diameter of each microcapillary therein, anddetermining the average of those measurements. The diameter measurementis conducted by cutting a cross section of the extruded article andobserving under an optical microscope fitted with a scale to measure thesize of the micro-capillary.

In one or more embodiments, the ratio of the thickness of the polymericcoating to the average diameter of the microcapillaries can be in therange of from 2:1 to 400:1

The spacing of the microcapillaries can vary depending on the desiredproperties to be achieved. Additionally, the spacing of themicrocapillaries can be defined relative to the diameter of themicrocapillaries. For instance, in various embodiments, themicrocapillaries can be spaced apart a distance of less than 1 times theaverage diameter of the microcapillaries, and can be as high as 10 timesthe average diameter of the microcapillaries. In various embodiments,the microcapillaries can be spaced apart an average of 100 to 5,000 μm,an average of 200 to 1,000 μm, or an average of 100 to 500 μm. Themeasurement “spaced apart” shall be determined on an edge-to-edge basis,as illustrated by “s” in FIG. 2C.

In various embodiments, when the microcapillary material is a gas atroom temperature (e.g., air), the microcapillary coating can have adensity that is at least 5%, at least 10%, at least 15%, at least 20%,at least 25%, or at least 30% less than an identical coating preparedfrom the same polymeric matrix material but not having microcapillaries.Additionally, the polymeric coating can have a density in the range offrom 5 to 40%, from 10 to 35%, or from 15 to 30% less than an identicalcoating prepared from the same polymeric matrix material but not havingmicrocapillaries.

In one or more embodiments, when the microcapillary material is a gas atroom temperature (e.g., air), the polymeric coating can have a reductionin tensile strength of less than 50%, less than 45%, less than 40%, lessthan 35%, or less than 30% relative to an identical coating preparedfrom the same polymeric matrix material except not havingmicrocapillaries. Additionally, the microcapillary coating can have areduction in tensile strength in the range of from 10 to 50%, or from 20to 45% relative to an identical coating prepared from the same polymericmatrix material except not having microcapillaries.

In various embodiments, when the microcapillary material is a gas atroom temperature (e.g., air), the polymeric coating can have a reductionin elongation-at-break of less than 30%, or less than 25% relative to anidentical coating prepared from the same polymeric matrix materialexcept not having microcapillaries. Additionally, the polymeric coatingcan have a reduction in elongation-at-break in the range of from 5 to30%, or from 10 to 25% relative to an identical coating prepared fromthe same polymeric matrix material except not having microcapillaries.

In various embodiments, when the microcapillary material is anelastomer, the polymeric coating can have higher flexibility, especiallyat low temperature, and reduced density because of the presence of lowerdensity elastomer in the microcapillary.

Optical Fiber Cable

In various embodiments, an optical fiber cable can be prepared thatincludes at least one optical fiber transmission medium (e.g., opticfiber) and an elongated polymeric protective component (e.g., a buffertube) surrounding at least a portion of the optical fiber transmissionmedium, where the polymeric protective component comprises a polymericmatrix material and a plurality of microcapillaries extendingsubstantially in the direction of elongation of the polymeric material.At least a portion of the microcapillaries contain a polymericmicrocapillary material. As explained in greater detail, below, in thisembodiment, the polymeric matrix material has a higher flexural modulusthan the polymeric microcapillary material.

A cross-sectional view of a common loose buffer tube optical fiber cabledesign is shown in FIG. 11. In this design of optical fiber cable(1001), buffer tubes (1002) are positioned radially around a centralstrength member (1004), with a helical rotation to the tubes in theaxial length. The helical rotation allows bending of the cable withoutsignificantly stretching the tube or the optic fibers (1006).

If a reduced number of buffer tubes is required, then foamed filler rodscan be used as low-cost spacers to occupy one or more empty buffer tubepositions (1010) to maintain cable geometry. The cable jacket (1014) isgenerally fabricated from a polyethylene-based material.

The buffer tubes (1002) are typically filled with an optic cable greaseor gel (1008). Various gel compounds are available commercially, anumber of which are hydrocarbon-based greases incorporating hydrocarbonoils, for example. These greases and gels provide the suspension andprotection needed in the immediate environment surrounding the fibers,including eliminating air space. This filling compound (also referred toas “gel” or “grease”) provides a barrier against water penetration,which is detrimental to the optic transmission performance.

Many other buffer tube cable designs are possible. The size andmaterials of construction for the central strength and tensile member,the dimensions and number of buffer tubes, and the use of metallicarmors and multiple layers of jacketing material are among the designelements.

A cross-sectional view of a typical core-tube optical fiber cable, alsoknown as “central tube,” is illustrated in FIG. 12. Bundles (1024) ofthe optical fibers (1022) are positioned near the center of the opticalcable (1020) within a central, cylindrical core tube (1028). The bundlesare embedded in a filling material (1026). Water blocking tape (1032)surrounds the ripcords (1030), which are on the surface of the core tube(1028). A corrugated, coated steel cylinder (1034) surrounds the tape toprotect the bundles (1024). Wire strength members (1036) provide thecable (1020) with strength and stiffness. A jacket (1038), which isgenerally fabricated from a polyethylene-based material, surrounds allof the components. In this design, the mechanical functions areincorporated into the outer sheathing system composed of the core tube,polyolefin jacketing layers, tensile and compressive strength members,metallic armors, core wraps, water blocking components, and othercomponents.

A core tube is typically larger in diameter than a buffer tube toaccommodate bundles of fibers or the use of ribbon components containingthe optic fibers. Color-coded binders are typically used to bundle andidentify the fibers. A core tube can contain water blocking grease orsuper-absorbent polymer elements surrounding the optic fiber components.The optimal material characteristics for a core tube component are oftensimilar to those of the buffer tube application.

An optical fiber cable, such as those described above, can typically bemade in a series of sequential manufacturing steps. Optical transmissionfibers are generally manufactured in the initial step. The fibers canhave a polymeric coating for mechanical protection. These fibers can beassembled into bundles or ribbon cable configurations or can be directlyincorporated into the cable fabrication.

Optical protective components can be manufactured using an extrusionfabrication process. Typically, a single screw plasticating extruderdischarges a fluxed and mixed polymer under pressure into a wire andcable cross-head. The cross-head can comprise any of the die assembliesfor producing microcapillary products described above. The cross-headturns the melt flow perpendicular to the extruder and shapes the flowinto the molten component. For buffer and core tubes, one or more opticfibers or fiber assemblies and grease are fed into the back of thecross-head and exit the cross-head within the molten tube that is thencooled and solidified in a water trough system. This component iseventually collected as a finished component on a take-up reel.

To control excess fiber length, a tensioning system is used to feed thefiber components into the tube fabrication process. In addition,component materials selection, the tube extrusion and cross-headequipment, and processing conditions are optimized to provide a finishedcomponent where post extrusion shrinkage does not result in excessiveslack in the optic fiber components.

The extruded optical protective components, along with other componentssuch as central components, armors, wraps, are then subsequentlyprocessed in one or more steps to produce the finished cableconstruction. This typically includes processing on a cabling line wherethe components are assembled with a fabricating extruder/crosshead thenused to apply the polymeric jacketing.

In the instant case, the above-described annular microcapillary productscan be used for one or more of the optical fiber cable componentsdescribed in FIGS. 11 and 12. For example, annular microcapillaryproducts may be employed in making fiber-protection components intypical fiber optic cable constructions, such as the buffer tubes (1002)and the cylindrical core tube (1028). FIG. 11 depicts microcapillaries(1016) disposed in buffer tube (1002). Similarly, FIG. 12 depictsmicrocapillaries (1040) disposed in the cylindrical core tube (1028). Asdiscussed above, the microcapillaries (1016, 1040) may contain amicrocapillary material, such as a polymeric microcapillary material.

One or more embodiments of the present invention contemplate a polymericprotective component (e.g., a buffer tube) prepared from an annularmicrocapillary product having a relatively high-modulus polymeric matrixmaterial and a relatively low-modulus polymeric microcapillary material,where the flexural modulus of the polymeric matrix material is highrelative to the polymeric microcapillary material and the flexuralmodulus of the polymeric microcapillary material is low relative to thepolymeric matrix material.

Generally, the high-modulus polymeric matrix material can have aflexural modulus of at least 310,000 psi, or in the range of from310,000 to 800,000 psi, from 325,000 to 700,000 psi, or in the range offrom 330,000 to 600,000 psi. By way of example, a typical flex modulusfor poly(p-phenylene sulfide) (“PPS”) is about 600,000 psi, forpolyether-ether-ketone is about 590,000 psi, for polycarbonate is about345,000 psi, for polyethylene terephthalate is about 400,000 psi, forpolybutylene terephthalate is about 330,000 psi, and for nylon 6/6 isabout 400,000 psi (all unfilled).

Additionally, the high-modulus polymeric matrix material can have atensile modulus of at least 300,000 psi, or in the range of from 300,000to 800,000 psi, from 300,000 to 750,000 psi, or from 325,000 to 740,000psi. By way of example, a typical tensile modulus for poly(p-phenylenesulfide) (“PPS”) is about 730,000 psi, for polyether-ether-ketone isabout 522,000 psi, for polycarbonate is about 345,000 psi, forpolyethylene terephthalate is about 471,000 psi, for polybutyleneterephthalate is about 377,000 psi, and for nylon 6/6 is about 350,000psi (all unfilled).

The high-modulus polymers are generally known as high-performancepolymers exhibiting high heat resistance (as measured by the heatdeflection temperature for example), excellent mechanical properties, aswell as abrasion and chemical resistance properties. They are, however,typically higher density polymers, having densities generally greaterthan 1.3 g/cm³.

In various embodiments, the polymeric matrix material of the opticalfiber buffer tube can comprise polybutylene terephthalate (“PBT”),polyethylene terephthalate (“PET”), a polycarbonate, a polyamide (e.g.,a nylon), polyether-ether-ketone (“PEEK), or combinations of two or morethereof. In an embodiment, the polymeric matrix material of the opticalfiber buffer tube comprises PBT.

The low-modulus polymeric microcapillary material can have a flexuralmodulus of less than 250,000 psi, or in the range of from 100 to 250,000psi, or from 500 to 200,000 psi. By way of example, a typicalhigh-density polyethylene has a flexural modulus of about 200,000 psi, atypical low-density polyethylene has a flexural modulus of about 30,000psi, typical thermoplastic polyurethane has a flexural modulus of about10,000 psi, and a typical polyolefin elastomer (e.g., ENGAGE™ 8402) hasa flexural modulus of about 580 psi.

Additionally, the low-modulus polymeric matrix material can have atensile modulus of less than 300,000 psi, or in the range of from 50 to300,000 psi, from 100 to 290,000 psi, from 200 to 290,000 psi, or from800 to 170,000 psi. By way of example, a typical high-densitypolyethylene has a tensile modulus of about 160,000 psi, a typicallow-density polyethylene has a tensile modulus of about 40,000 psi,typical thermoplastic polyurethane has a tensile modulus of about 8,000psi, and a typical polyolefin elastomer (e.g., ENGAGE™ 8402) has atensile modulus of about 970 psi.

The low-modulus materials are generally characterized by highflexibility and excellent impact resistance, even at low temperatures.These resins can have a melt index ranging from less than 1.0 to greaterthan 1,000 g/10 minutes such as, for example, AFFINITY™ GA grades ofolefin elastomer, commercially available from The Dow Chemical Company.These polyolefin elastomer resins can also have a density as low as0.857 g/cm³ and a melting point as low as 38° C. such as ENGAGE™ 8842also from The Dow Chemical Company.

In one or more embodiments, the polymeric microcapillary material of theoptical fiber buffer tube can comprise any of the ethylene-basedpolymers described above (e.g., HDPE, LDPE, EEA, EVA); olefin elastomers(such as described above) and other ethylene copolymers such asAFFINITY™, ENGAGE™, and VERSIFY™ copolymers, commercially available fromThe Dow Chemical Company; olefin block copolymers (such as thosecommercially available under the trade name INFUSE™ from The DowChemical Company, Midland, Mich., USA), mesophase-separated olefinmulti-block interpolymers (such as described in U.S. Pat. No.7,947,793), olefin block composites (such as described in U.S. PatentApplication Publication No. 2008/0269412, published on Oct. 30, 2008),or combinations of two or more thereof. In an embodiment, the polymericmicrocapillary material of the optical fiber buffer tube comprises HDPE.

When used in an optical fiber cable construction, the polymericprotective component can have a thickness selected depending on thecable size and construction. In various embodiments, the polymericprotective component can have a thickness ranging from 5 to 20 mils(about 127 to 508 μm). Additionally, the average diameter of themicrocapillaries in the polymeric protective component can be selecteddepending on the thickness chosen for the polymeric protectivecomponent. In one or more embodiments, the ratio of the thickness of thepolymeric protective component to the average diameter of themicrocapillaries can be in the range of from 2:1 to 400:1. Additionally,the spacing of the microcapillaries can be defined relative to thediameter of the microcapillaries. For instance, in various embodiments,the microcapillaries can be spaced apart a distance of less than 1 timesthe average diameter of the microcapillaries, and can be as high as 10times the average diameter of the microcapillaries. In variousembodiments, the microcapillaries can be spaced apart an average of 100to 5,000 μm, an average of 200 to 1,000 μm, or an average of 100 to 500μm.

In various embodiments, the polymeric protective component can have ashrinkback of less than 0.1%, less than 0.08%, less than 0.05%, lessthan 0.03%, or less than 0.01%. In various embodiments, the polymericprotective component can have a shrinkback of 0%. Shrinkback isdetermined according to the procedure provided in PCT PublishedApplication WO 2014/099350 at paragraph [0068]. Shrinkback is determinedafter samples are aged in an oven for five temperature cycles of40-100-40° C. over a period of 27 hours.

In various embodiments, the polymeric protective component can have aweight gain (or grease resistance) of less than 3%, less than 2%, lessthan 1%, or less than 0.5% after aging at a temperature of 85° C. for 14days in LA 444. Grease resistance is determined according to theprocedure provided in the Test Methods section, below.

Test Methods

Density

Density is determined according to ASTM D 792.

Melt Index

Melt index, or I₂, is measured in accordance with ASTM D 1238, condition190° C./2.16 kg, and is reported in grams eluted per 10 minutes.

Tensile Strength

Measure tensile strength, tensile modulus and elongation according toASTM D 638.

Shrinkback

Measure shrinkback using the procedure provided in PCT PublishedApplication WO 2014/099350 at paragraph [0068], except that samplespresently tested are in tape form. Shrinkback is determined aftersamples are aged in an oven for five temperature cycles of 40-100-40° C.over a period of 27 hours.

Gel Pickup

Measure gel pickup using the following procedure. The tape specimens arefirst weighed then coated with a buffer tube filling gel (LA444, TheStewart Group), placed in an aluminum pan with a gel layer at thebottom, then covered with another layer of gel. The pan containing thesamples is then placed in an oven set at 85° C. and aged for 14 days. Atthe end of the aging period, the tapes are removed, wiped clean andweighed again. The amount of gel picked up is calculated as a percentagebased on the aged sample weight relative to the initial weight of thesample.

Materials

The following materials are employed in the Examples, below.

AXELERON™ CS L-3364 NT is a high-density polyethylene (“HDPE”) having anominal density of 0.947 g/cm³, a melt index (I₂) in the range of from0.65 to 0.9 g/10 min. and is commercially available from The DowChemical Company, Midland, Mich., USA.

The polybutylene terephthalate (“PBT”) is PBT-61008, which has a densityof 1.34 g/cm³, a melt index of 8.25 g/10 min. at 250° C., and a meltingpoint of 224° C. PBT-61008 is commercially available from ZuzhouYing-mao Plastic Co., Ltd. (PRC).

LA444 is a buffer tube filling gel, which is commercially available fromThe Stewart Group (Ontario, Canada).

Examples

Sample Preparation

Microcapillary Samples

Prepare one sample (S1) and one comparative sample (CS1) using atape-extrusion system consisting of two single-screw extruders (1.9-cmand 3.81-cm Killion extruders) fitted with a microcapillary die capableof handling two polymer melt streams. This line consists of a 3.81-cmKillion single-screw extruder to supply polymer melt for the matrixmaterial and a 1.9-cm Killion single-screw extruder to supply polymermelt for the microcapillaries via a transfer line to the microcapillarydie. The die to be used in these Examples is described in detail in PCTPublished Patent Application No. WO 2014/003761, specifically withrespect to FIGS. 4A and 4A1, and the corresponding text of the writtendescription, which is incorporated herein by reference. The die has 42microcapillary nozzles, a width of 5 cm, and a die gap of 1.5 mm. Eachmicrocapillary nozzle has an outer diameter of 0.38 mm and an innerdiameter of 0.19 mm.

Sample S1 and comparative sample CS1 are prepared as follows. First, theextruders, gear pump, transfer lines, and die are heated to theoperating temperatures with a “soak” time of about 30 minutes. Thetemperature profiles for the 3.81-cm and 1.9-cm Killion single-screwextruders are given in Table 1, below. Microcapillary polymer resins arecharged into the hopper of the 1.9-cm Killion single-screw extruder, andthe screw speed is turned up to the target value (60 rpm). As thepolymer melt exits the microcapillary nozzles, the matrix polymer resinsare filled into the hopper of 3.81-cm Killion single-screw extruder andthe main extruder is turned on. The extruder screw of the 3.81-cmKillion single-screw extruder feeds the melt to a gear pump, whichmaintains a substantially constant flow of melt towards themicrocapillary die. Then, the polymer melt from the 3.81-cm Killionsingle-screw extruder is divided into two streams, which meet withpolymer strands from microcapillary nozzles. Upon exiting the extrusiondie, the extrudate is cooled on a chill roll on a rollstack. Once theextrudate is quenched, it is taken by a nip roll. The line speed iscontrolled by a nip roll in the rollstack.

TABLE 1 Temperature Profiles of the 3.81-cm and 1.9-cm KillionSingle-Screw Extruders Extruder Extruder Extruder Extruder AdaptorTransfer Screen Feed Die Zone 1 Zone 2 Zone 3 Zone 4 Zone Line Changerblock Zone Extruders (° F.) (° F.) (° F.) (° F.) (° F.) (° F.) (° F.) (°F.) (° F.) 3.81-cm 338 428 464 482 482 482 482 482 482 Killion Extruder1.9-cm 356 464 482 482 Killion Extruder

The extrusion system is set up to supply two polymer melt streams: afirst polymer (3.81-cm Killion extruder) to make a continuous matrixsurrounding a second polymer (1.9-cm Killion extruder) shaped asmicrocapillaries embedded in the first polymer. The first polymer(matrix) of S1 is PBT, and the second polymer (microcapillary) of S1 isHDPE. The first polymer (matrix) of CS1 is HDPE, and the second polymer(microcapillary) of CS1 is PBT. The processing conditions andmicrocapillary dimension for S1 and CS1 are given in Table 2, below.

Estimated from density measurements, S1 contains 26.5 weight percent ofthe microcapillary material (HDPE) and CS1 contains 13.2 weight percentof the microcapillary material (PBT).

TABLE 2 Processing Conditions and Microcapillary Dimensions for S1 andCS1 CS1 S1 Matrix Material HDPE (DGDL- PBT 3364NT) MicrocapillaryMaterial PBT HDPE (DGDL- 3364NT) Screw Speed of 3.81-cm 15 15 Extruder(rpm) Screw Speed of 1.9-cm Extruder 30 60 (rpm) Line Speed (ft/min) 5 5Average Film Thickness 1.054 1.143 (mm) Average Film Width (cm) 4.5 5Area Percentage of 20.1 18.1 Microcapillaries in the Film (%) Long Axisof a 0.706 0.600 Microcapillary (mm) Short Axis of a 0.356 0.466Microcapillary (mm) Space between Two 0.373 0.574 Microcapillaries (mm)Film Surface to Inner 0.317 0.373 Surface of Microcapillary (mm)Control Samples

Control sample 1 (“Control 1”) is unmodified HDPE. Control sample 2(“Control 2”) is unmodified PBT. Tape samples of Control 1 and 2 areprepared by the same experimental protocol and extrusion conditionsdescribed above for samples S1 and CS1, except that the microcapillariesare filled with the same material as the matrix. The processingconditions and microcapillary dimension for Control 1 and Control 2 aregiven in Table 3.

TABLE 3 Processing Conditions and Microcapillary Dimensions for Control1 and Control 2 Control 1 Control 2 Matrix Material HDPE (DGDL- PBT3364NT) Microcapillary Material HDPE (DGDL- PBT 3364NT) Screw Speed of3.81-cm 15 15 Extruder (rpm) Screw Speed of 1.9-cm Extruder 30 30 (rpm)Line Speed (ft/min) 5 5 Average Film Thickness 1.003 1.008 (mm) AverageFilm Width (cm) 4.6 5

Example—LDPE Microcapillary Tape Analysis

Analyze each of S 1, CS1, Control 1, and Control 2 according to the TestMethods provided above. The results are provided in Table 4, below.

TABLE 4 Properties of Control 1, Control 2, CS1, and S1 Control 1Control 2 (HDPE) (PBT) CS1 S1 Density (g/cm³) 0.945 1.304 0.986 1.208Tensile Strength (psi) 4,016 6,524 2,663 4,904 Tensile Modulus (psi)4.22E+04 4.16E+05 8.19E+04 2.23E+05 Shrinkback (%) 0.31 0 0.16 0 Gelpick up after aging 4.31 0 3.59 0.41 (%) Aged* tensile strength 2,1836,867 2,614 6,252 (psi) *As aged for gel pick up testing

As can be seen from the results provided in Table 1, S1, which employsPBT as a matrix material with HDPE as microcapillary material, shows areduction in tensile strength and lower density (desired) compared topure PBT (Control 2); however, S1 has a density about 1.4 times higherthan HDPE (Control 1). The modulus of S1 higher than HDPE and lowerversus PBT, indicating improved flexibility, and the shrinkback istypical of pure PBT and well less than pure HDPE and CS1. After aging,gel pickup in S1 is about 10 times lower compared to pure HDPE, andpost-aging tensile strength is much closer to the PBT control than HDPE(i.e., no loss, but rather an increase, which reflects PBT behaviorunder 85° C. aging as seen in the pure PBT construction of Control 2).

The invention claimed is:
 1. An optical fiber cable, comprising: (a) atleast one optical fiber transmission medium; and (b) at least oneannular, elongated polymeric protective component surrounding at least aportion of said optical fiber transmission medium, wherein said annular,elongated polymeric protective component comprises a polymeric matrixmaterial and a plurality of microcapillaries which extend substantiallyin the direction of elongation of said annular, elongated polymericprotective component, wherein at least a portion of saidmicrocapillaries contain a polymeric microcapillary material, whereinsaid polymeric matrix material has a higher flexural modulus than saidpolymeric microcapillary material, wherein said annular, elongatedpolymeric protective component is a buffer tube, wherein at least one ofan optic cable grease or gel is disposed within said annular, elongatedpolymeric protective component.
 2. The optical fiber cable of claim 1,wherein said polymeric matrix material has a flexural modulus in therange of from 300,000 to 800,000 psi; wherein said polymericmicrocapillary material has a flexural modulus in the range of from 100to 250,000 psi.
 3. The optical fiber cable of claim 1, wherein saidpolymeric protective component exhibits a shrinkback of less than 0.1percent.
 4. The optical fiber cable of claim 1, wherein said polymericprotective component has a weight gain of less than 3 percent afteraging at a temperature of 85° C. for 14 days in LA
 444. 5. The opticalfiber cable of claim 1, wherein said polymeric matrix material isselected from the group consisting of polybutylene terephthalate(“PBT”), polyethylene terephthalate (“PET”), a polycarbonate, apolyamide, polyether-ether-ketone (“PEEK”), or combinations of two ormore thereof.
 6. The optical fiber cable of claim 5, wherein saidpolymeric matrix material is PBT.
 7. The optical fiber cable of claim 1,wherein said polymeric microcapillary material is selected from thegroup consisting of an ethylene-based polymer, an olefin elastomer, anolefin block copolymer, a mesophase-separated olefin multi-blockinterpolymer, an olefin block composite, or combinations of two or morethereof.
 8. The optical fiber cable of claim 7, wherein said polymericmicrocapillary material is high-density polyethylene.
 9. The opticalfiber cable of claim 1, wherein said polymeric matrix material ispresent in the form of a multi-layer construction.
 10. The optical fibercable of claim 1, wherein the ratio of the thickness of said polymericprotective component to the average diameter of said microcapillaries isin the range of from 2:1 to 400:1.